Safety-valve.



D. COCKBURN & D. MAONIGOLL.

SAFETY VALVE. LAIPLIOATION TILED JULY 11, 1911.

1 $126,734, Patented May 21, 1912;

2 SHEETSSHEET 2.

I I \u i {I E z y z E k R Q A s v wiinessex- [nveniarsu COLUMBIA FLANOdRAPl-l IO-,WASHINEITON, D. c.

D. GOGKBURN & D. MAONIGOLL.

SAFETY VALVE.

APPLICATION FILED JULY 11,1911.

1,026,734, Patented May 21,1912.

.2 SHEETS-SHEET 1.

wiinassejst lwve'niovx- ,w wwwmuee COLUMBIA PLANOGRAH 50., WASHINGTON. D C.

DAVID COOKBURN AND DONALD MAONICOLL, 0F CARIDONALD, GLASGOW, SCOTLAND.

SAFETY-VALVE.

Specification of Letters Patent.

Application filed July 11, 1911.

Patented May 21, 1912. Serial No. 637,968.

a piston connected to a pilot valve, and a device for moving the pilot valve and thereby moving both pistons and lifting the main valve off its seat.

The novelty of the invention consists in the combination of elements hereinafter particularly described and pointed out in the claims.

In the accompanying drawings, Figure l is a front elevation and Fig. 2 is a vertical section at right angles thereto showing, by way of example, a safety valve of the double outlet type equipped with the improvements.

Referring to the drawings, the safety valve comprises a casing A, provided with inlet and outlet branches-B and C, and having located within it main valves D which are adapted to be controlled by springloaded pilot valves E, each seated within a casing F mounted eXteriorly of the casing A and communicating with the atmosphere by means of openings F in the sides of said casing F. The spindle L of each pilot valve has attached to it a nut N which nut N is retained loosely within a piston P by means of a nut N Each piston P has a number of grooves WV on its circumference and is fitted and retained, by means of a removable flanged portion 37, within ahollow piston P connected to the corresponding main valve D, the chamber receiving the piston P communicating with the inlet branch B by means of passages H when the main valve is closed, and communicating with the inlet branch B by means of a pas sage H, when the main valve is open. The piston P operates within a cylindrical passage J formed on the casing A.

Each main valve D isconnected to a cap 0 by means of a spindle D which passes through said casing A, and is kept closed, when no fluid pressure is present, by means of springs K interposed between said cap and said casing, said cap serving as a means torotatethe main valve, if desired. The springs K for closing the pilot valves E are each located within the casing F and extend between the outer end of said casing and a flange L on a spindle L engaging the respective valve E, each of said pilot valves being operated manually, if desired, or rotated on its seat, through the intermediary of the spindle L which is provided with a handle L Each of the pilot valves E is adapted to be raised from its seat by means of an arm D secured to a rock shaft D which is operated so as to cause said arm D to press on a projection on the pilot valve, which operation also causes the corresponding main valve D to be raised oif its seat by reason of the piston P abutting against the flange port-ion p.

The action of the valves being the same in each case, the following description of the operation of one of the valves will suffice Fluid under pressure enters the casing A by way of the inlet branch B, escapes past the rings R of the piston P, enters through the passages H then past the piston P to the outer end of the cylindrical passage J, whereupon pressure is exerted on the underside of the pilot valve E. lVhen the pressure in the cylinder J accumulates so as to equal that in the inlet B, pressure is exerted on the main valve D, which is thus kept closed. When the pressure becomes excessive, the pilot valve is raised off its seat and permits fluid in the cylinder J to escape to the atmosphere, the pilot valve meanwhile being kept in this position through the eX- cess pressure exerted on the inner end of the piston P The main valve D is now opened by the pressure on the difference between the larger area of the piston P and the smaller area of the valve D less the pressure on the area of the piston P The main valve now being opened, the fluid pressure is then supplied to the inner side of the piston P by way of the passage H, and the main supply of fluid passes the main valve D to the outlet 0. When the fluid pressure falls, the pilot valve closes whereupon the pressure fluid passing the rings R and piston P accumulates in the cylinder J so as to equal that in the inlet B; thereupon the main valve D is closed by the pressure on the valve D. The action of the spring K has been neglected in these considerations, it being understood that the spring is not strong enough to prevent the valve from being fully opened.

Having now described our invention what we claim and desire to secure by Letters Patent of the United States is 1. A safety valve comprising, in combination, a casing provided with inlet and outlet branches, and having a cylindrical passage J between said branches and at one side thereof, a .main valve seated within said casing and arranged coaxial with said passage and having an extension providing a hollow piston 1 movable with said main valve and adapted to operate within said cylindrical passage, said hollow piston having one or more steam inlets to its chamber, a spring-closed pilot valve for controlling said main valve, said pilot valve being seated exteriorly of said passage and arranged in line with the said main valve, a hollow piston P within the chamber of the said hollow piston P, a nut fitting loosely within said hollow piston P, a rod connecting said nut with said pilot valve, means for retaining said nut in the chamber of said piston P and means for lifting said pilot valve from its seat.

2. A safety valve comprising, in combination, a casing provided with inlet and outlet branches, and having a cylindrical passage J between said branches and at one side thereof, a main valve seated within said casing and arranged coaxial with said passage and having an extension providing a hollow piston P movable with said main valve and adapted to operate within said cylindrical passage, said hollow piston having one or more steam inlets to its chamber, a springclosed pilot valve for controlling said main valve, said pilot valve being seated eXteriorly of said passage and arranged in line with the said main valve, a hollow piston P within the chamber of the said hollow piston P, a nut fitting loosely within said hollow piston P, a rod connecting said nut with said pilot valve, means for retaining said nut in the chamber of said piston P and a rocking device for lifting said pilot valve from its seat, and thus serving, through the said pilot valve, to operate both of said pistons and also the main valve.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

DAVID COCKBURN. DONALD MAQNICOLL.

Witnesses:

JOHN MCGLEARY, THoMAs BISHOP GRAHAM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents- Washington, D. G. 

